1. Field of the Invention
The present invention relates to a medical aspirator for aspirating, for example, thrombus, phlegm, and a body fluid such as blood.
2. Related Background Art
Conventionally, medical aspirators have been used in wide fields such as intraoral treatment for a patient at home or a patient in a hospital and aspiration of a body fluid such as blood at the time of a surgical operation.
However, these medical aspirators have a significant problem in that they are inferior in portability.
First, a first point concerning the problem of portability will be hereinafter described.
In general, in a medical aspirator, a reciprocating type electric pump has a larger startup load compared with a rotary electric pump. This is because startup energy loss of a mechanism for converting a rotational movement into a reciprocating movement is large. Therefore, special attention should be paid to the medical aspirator so that a sufficient startup property can be obtained in the medical aspirator that employs a reciprocating type electric pump.
Incidentally, in a diaphragm pump, which is one of the reciprocating type electric pumps, a pump mechanism section and a pump chamber are completely shielded and separated by a film. Thus, the diaphragm pump has a characteristic that contamination through the pump chamber is extremely little. Consequently, the diaphragm pump is widely used for various medical instruments. However, in a case in which the pump is stopped, since a negative pressure in the shut-off pump chamber is maintained, a restarting load increases. Thus, it is particularly hard to restart a diaphragm pump.
This problem is particularly conspicuous in portable or mobile medical instruments, medical instruments for surgical operations, or the like. In the portable or mobile medical instruments, various cells are used as a power supply. However, cells as small and light as possible are used for convenience of carrying. Thus, it is difficult to obtain a sufficient output overcoming a high load at the time of restart. In addition, in the medical instruments for surgical operations, in order to avoid contamination in a human body, a portion from a pump chamber to a body insertion part should be completely closed. In addition, during progress of an operation, emergency stopping or restarting may be required. Thus, reliability of restart is a significant issue involving life or death for a patient.
Currently, medical aspirators are used in a wide variety of fields such as intraoral treatment for a patient at home or a patient in hospital and aspiration of the body fluid such as blood at the time of a surgical operation. In addition, in recent years, medical aspirators have frequently been used for a percutaneous thrombus removal operation with a catheter being inserted in a coronary artery to aspirate thrombus.
In a conventional commercially available aspirator for a percutaneous thrombus removal operation, restart after emergency stop is performed by temporarily removing a coupling tube, which connects an aspirate sampling bottle and an aspiration port, from the aspiration port to open the aspirator to provide atmospheric pressure in the aspirator and then connecting the coupling tube to the aspiration port again to turn on a power supply.
However, it takes a lot of time and labor to perform these manipulations during an operation requiring urgency. In addition, since the coupling tube is connected to the aspiration port, which has a complicated shape, there is the likelihood of air leakage due to a connection failure or contamination of the aspirator via bloodstained gloves, which may result in spreading of a disease to other patients.
Next, a second point concerning the problem of portability will be hereinafter described.
At the time of aspirating a body fluid or the like, in particular, aspirating a coronary artery thrombus which is a cause of myocardial infarction, clogging frequently occurs in an aspiration catheter due to the thrombus during thrombus aspiration. In the present situation, an operator checks the clogging in the aspiration catheter by monitoring movement of an aspirate (blood) in the aspiration catheter or an aspiration tube, or in an aspirate sampling bottle. However, this monitoring work is a significant burden for the operator who is manipulating a catheter in a blood vessel for acute myocardial infarction which requires urgency. Thus, the clogging due to thrombus leads not only to a decrease in aspiration efficiency but also to a decrease in safety for a patient. In the worst case, the clogging is an issue of life and death for a patient.
This problem is conspicuous in a medical aspirator including an electric pump for vacuum aspiration or a medical aspirator including an internal power supply such as a cell. In other words, since importance is attached to portability in both the aspirators, a compact pump with less power consumption or a cell with relatively small capacity is inevitably selected. Consequently, there is not much margin in an aspiration force, and clogging of thrombus or the like particularly easily occurs.